Preliminary evidence of segregation distortion in the SLA system.

The segregation of 11 well-defined SLA haplotypes was investigated in 40 Land-race and 48 Large White Danish and Swiss litters. Among the 11 haplotypes, the segregation of one (SLA 20-8.2.11) deviated significantly from the expected 1:1 segregation ratio in back-cross families. Tests indicated that these families were homogeneous with respect to segregation distortion, although the distortion was more pronounced in litters sired by heterozygous Danish boars than by heterozygous Swiss boars and Danish and Swiss sows. The data presented do not allow any definite conclusion about the cause of the segregation distortion. The possibility of the distortion being caused either by a complex similar to the T/t-complex found in mouse and contemplated in man or directly by the SLA region is discussed.